Chapter 16 Energy Efficiency and Renewable Energy

16-4 What Are the Advantages and Disadvantages of Using Hydropower Concept 16-4 We can use water flowing over dams, tidal flows, and ocean waves to generate electricity, but environmental concerns and limited availability of suitable sites may limit the use of these energy resources.

We Can Produce Electricity from Falling and Flowing Water Hydropower Uses kinetic energy of moving water Indirect form of solar energy World’s leading renewable energy source used to produce electricity Advantages and disadvantages Micro-hydropower generators

Tradeoffs: Dams and Reservoirs Figure 13.13: Trade-offs. Large dams and reservoirs have advantages (green) and disadvantages (orange) (Concept 13-3). The world’s 45,000 large dams (15 meters (49 feet) or higher) capture and store about 14% of the world’s surface runoff, provide water for almost half of all irrigated cropland, and supply more than half the electricity used in 65 countries. The United States has more than 70,000 large and small dams, capable of capturing and storing half of the country’s entire river flow. Question: Which single advantage and which single disadvantage do you think are the most important? Fig. 13-13, p. 328

Powerlines Reservoir Dam Powerhouse Intake Turbine Figure 13.13: Trade-offs. Large dams and reservoirs have advantages (green) and disadvantages (orange) (Concept 13-3). The world’s 45,000 large dams (15 meters (49 feet) or higher) capture and store about 14% of the world’s surface runoff, provide water for almost half of all irrigated cropland, and supply more than half the electricity used in 65 countries. The United States has more than 70,000 large and small dams, capable of capturing and storing half of the country’s entire river flow. Question: Which single advantage and which single disadvantage do you think are the most important? Fig. 13-13b, p. 328

Trade-Offs: Large-Scale Hydropower, Advantages and Disadvantages Figure 16.22: Using large dams and reservoirs to produce electricity has advantages and disadvantages (Concept 16-4). Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Fig. 16-22, p. 415

Tides and Waves Can Be Used to Produce Electricity Produce electricity from flowing water Ocean tides and waves So far, power systems are limited Disadvantages Few suitable sites High costs Equipment damaged by storms and corrosion

16-5 What Are the Advantages and Disadvantages of Using Wind Power? Concept 16-5 When we include the environmental costs of using energy resources in the market prices of energy, wind power is the least expensive and least polluting way to produce electricity.

Using Wind to Produce Electricity Is an Important Step toward Sustainability (1) Wind: indirect form of solar energy Captured by turbines Converted into electrical energy Second fastest-growing source of energy What is the global potential for wind energy? Wind farms: on land and offshore

World Electricity from Wind Energy Figure 12, Supplement 9

Solutions: Wind Turbine and Wind Farms on Land and Offshore Figure 16.23: Solutions. A single wind turbine (left) can produce electricity. Increasingly, they are interconnected in arrays of tens to hundreds of turbines. These wind farms or wind parks can be located on land (middle) or offshore (right). The land beneath these turbines can still be used to grow crops or to raise cattle. Questions: Would you object to having a wind farm located near where you live? Why or why not? Fig. 16-23, p. 417

Gearbox Electrical generator Power cable Wind turbine Figure 16.23: Solutions. A single wind turbine (left) can produce electricity. Increasingly, they are interconnected in arrays of tens to hundreds of turbines. These wind farms or wind parks can be located on land (middle) or offshore (right). The land beneath these turbines can still be used to grow crops or to raise cattle. Questions: Would you object to having a wind farm located near where you live? Why or why not? Wind turbine Fig. 16-23a, p. 417

Wind farm Figure 16.23: Solutions. A single wind turbine (left) can produce electricity. Increasingly, they are interconnected in arrays of tens to hundreds of turbines. These wind farms or wind parks can be located on land (middle) or offshore (right). The land beneath these turbines can still be used to grow crops or to raise cattle. Questions: Would you object to having a wind farm located near where you live? Why or why not? Wind farm Fig. 16-23b, p. 417

Wind farm (offshore) Figure 16.23: Solutions. A single wind turbine (left) can produce electricity. Increasingly, they are interconnected in arrays of tens to hundreds of turbines. These wind farms or wind parks can be located on land (middle) or offshore (right). The land beneath these turbines can still be used to grow crops or to raise cattle. Questions: Would you object to having a wind farm located near where you live? Why or why not? Wind farm (offshore) Fig. 16-23c, p. 417

Wind Turbine Figure 16.24: Maintenance workers get a long-distance view from atop a wind turbine, somewhere in North America, built by Suzlon Energy, a company established in India in 1995. Fig. 16-24, p. 417

Using Wind to Produce Electricity Is an Important Step toward Sustainability (2) Countries with the highest total installed wind power capacity Germany United States Spain India Denmark Installation is increasing in several other countries

Using Wind to Produce Electricity Is an Important Step toward Sustainability (3) Advantages of wind energy Drawbacks Windy areas may be sparsely populated – need to develop grid system to transfer electricity Winds die down; need back-up energy Storage of wind energy Kills migratory birds “Not in my backyard”

Trade-Offs: Wind Power Figure 16.25: Using wind to produce electricity has advantages and disadvantages (Concept 16-5). With sufficient and consistent government incentives, wind power could supply more than 10% of the world’s electricity and 20% of the electricity used in the United States by 2030. Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Fig. 16-25, p. 418

Case Study: The Astounding Potential of Wind Power in the United States “Saudi Arabia of wind power” North Dakota South Dakota Kansas Texas How much electricity is possible with wind farms in those states? Could create up to 500,000 jobs

United States Wind Power Potential Figure 24, Supplement 8

16-6 Advantages and Disadvantages of Using Biomass as an Energy Source Concept 16-6A Solid biomass is a renewable resource for much of the world’s population, but burning it faster than it is replenished produces a net gain in atmospheric greenhouse gases, and creating biomass plantations can degrade soil biodiversity. Concept 16-6B We can use liquid biofuels derived from biomass in place of gasoline and diesel fuels, but creating biofuel plantations can degrade soil and biodiversity and increase food prices and greenhouse gas emissions.

We Can Get Energy by Burning Solid Biomass Plant materials and animal waste we can burn or turn into biofuels Production of solid mass fuel Plant fast-growing trees Biomass plantations Collect crop residues and animal manure Advantages and disadvantages

Trade-Offs: Solid Biomass Figure 16.26: Burning solid biomass as a fuel has advantages and disadvantages (Concept 16-6a). Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Fig. 16-26, p. 420

We Can Convert Plants and Plant Wastes to Liquid Biofuels (1) Biodiesel Ethanol Biggest producers of biofuel The United States Brazil The European Union China

We Can Convert Plants and Plant Wastes to Liquid Biofuels (2) Major advantages over gasoline and diesel fuel produced from oil Biofuel crops can be grown almost anywhere No net increase in CO2 emissions if managed properly Available now

We Can Convert Plants and Plant Wastes to Liquid Biofuels (3) Studies warn of problems: Decrease biodiversity Increase soil degrading, erosion, and nutrient leaching Push farmers off their land Raise food prices Reduce water supplies, especially for corn and soy

Case Study: Is Biodiesel the Answer? Biodiesel production from vegetable oil from various sources 95% produced by the European Union Subsidies promote rapid growth in United States Advantages and disadvantages

Trade-Offs: Biodiesel Figure 16.27: Using biodiesel as a vehicle fuel has advantages and disadvantages compared to gasoline. Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Do you think that the advantages of biodiesel fuel outweigh its disadvantages? Fig. 16-27, p. 421

Case Study: Is Ethanol the Answer? (1) Ethanol from plants and plant wastes Brazil produces ethanol from sugarcane Environmental consequences United States: ethanol from corn Low net energy yield Reduce the need for oil imports? Harm food supply Air pollution and climate change?

Case Study: Is Ethanol the Answer? (2) Cellulosic ethanol: alternative to corn ethanol Switchgrass Crop residues Municipal wastes Advantages and disadvantages

World Ethanol Production Figure 13, Supplement 9

Bagasse is Sugarcane Residue Figure 16.28: Bagasse is a sugarcane residue that can be used to make ethanol. Fig. 16-28, p. 421

Natural Capital: Rapidly Growing Switchgrass Figure 16.29: Natural capital. The cellulose in this rapidly growing switchgrass can be converted into ethanol, but further research is needed to develop affordable production methods. This perennial plant can also help to slow projected climate change by removing carbon dioxide from the atmosphere and storing it as organic compounds in the soil. Fig. 16-29, p. 423

Trade-Offs: Ethanol Fuel Figure 16.30: Using ethanol as a vehicle fuel has advantages and disadvantages compared to using gasoline (Concept 16-6b). Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Fig. 16-30, p. 423

Case Study: Getting Gasoline and Diesel Fuel from Algae and Bacteria (1) Algae remove CO2 and convert it to oil Not compete for cropland = not affect food prices Wastewater/sewage treatment plants Could transfer CO2 from power plants Algae challenges Need to lower costs Open ponds vs. bioreactors Affordable ways of extracting oil Scaling to large production

Case Study: Getting Gasoline and Diesel Fuel from Algae and Bacteria (2) Bacteria: synthetic biology Convert sugarcane juice to biodiesel Need large regions growing sugarcane Producing fuels from algae and bacteria can be done almost anywhere

16-7 What Are the Advantages and Disadvantages of Geothermal Energy? Concept 16-7 Geothermal energy has great potential for supplying many areas with heat and electricity, and it has a generally low environmental impact, but sites where it can be used economically are limited.

Getting Energy from the Earth’s Internal Heat (1) Geothermal energy: heat stored in Soil Underground rocks Fluids in the earth’s mantle Geothermal heat pump system Energy efficient and reliable Environmentally clean Cost effective to heat or cool a space

Natural Capital: A Geothermal Heat Pump System Can Heat or Cool a House Figure 16.31: Natural capital. A geothermal heat pump system can heat or cool a house almost anywhere. It heats the house in winter by transferring heat from the ground into the house (shown here). In the summer, it cools the house by transferring heat from the house to the ground. Fig. 16-31, p. 425

Getting Energy from the Earth’s Internal Heat (2) Hydrothermal reservoirs U.S. is the world’s largest producer Hot, dry rock Geothermal energy problems High cost of tapping hydrothermal reservoirs Dry- or wet-steam geothermal reservoirs could be depleted Could create earthquakes

Geothermal Sites in the United States Figure 26, Supplement 8

Geothermal Sites Worldwide Figure 25, Supplement 8

Geothermal Power Plant in Iceland Figure 16.32: This geothermal power plant in Iceland produces electricity and heats a nearby spa called the Blue Lagoon. Fig. 16-32, p. 425

Trade Offs: Geothermal Energy Figure 16.33: Using geothermal energy for space heating and for producing electricity or high-temperature heat for industrial processes has advantages and disadvantages (Concept 16-7). Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Fig. 16-33, p. 426

16-8 The Advantages and Disadvantages of Using Hydrogen as an Energy Source Concept 16-8 Hydrogen fuel holds great promise for powering cars and generating electricity, but for it to be environmentally beneficial, we would have to produce it without the use of fossil fuels.

Will Hydrogen Save Us? (1) Hydrogen as a fuel Eliminate most of the air pollution problems Reduce threats of global warming Some challenges Chemically locked in water and organic compounds = net negative energy yield Expensive fuel cells are the best way to use hydrogen CO2 levels dependent on method of hydrogen production

Will Hydrogen Save Us? (2) Net negative energy yield Production and storage of H2 Hydrogen-powered vehicles: prototypes available Can we produce hydrogen on demand? Larger fuel cells – fuel-cell stacks

A Fuel Cell Separates the Hydrogen Atoms’ Electrons from Their Protons Figure 16.34: A fuel cell takes in hydrogen gas and separates the hydrogen atoms’ electrons from their protons. The electrons flow through wires to provide electricity, while the protons pass through a membrane and combine with oxygen gas to form water vapor. Note that this process is the reverse of electrolysis, the process of passing electricity through water to produce hydrogen fuel. The photo (right) shows a fuel-cell concept car introduced by Honda Motor Company in 2009 at an international car show in Toronto, Canada. All of the exhaust from this car is water vapor. Fig. 16-34, p. 427

Trade-Offs: Hydrogen, Advantages and Disadvantages Figure 16.35: Using hydrogen as a fuel for vehicles and for providing heat and electricity has advantages and disadvantages (Concept 16-8). Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Fig. 16-35, p. 428

Science Focus: The Quest to Make Hydrogen Workable Bacteria and algae can produce hydrogen through biodegrading organic material Use electricity from renewable energy sources to produce hydrogen Storage options for hydrogen

16-9 How Can We Make the Transition to a More Sustainable Energy Future? Concept 16-9 We can make the transition to a more sustainable energy future if we greatly improve energy efficiency, use a mix of renewable energy resources, and include environmental costs in the market prices of all energy resources.

Choosing Energy Paths (1) How will energy policies be created? Hard energy path Soft energy path

Choosing Energy Paths (2) General conclusions Gradual shift to smaller, decentralized micropower systems Transition to a diverse mix of locally available renewable energy resources Improved energy efficiency Fossil fuels will still be used in large amounts Natural gas is the best choice

Solutions: Decentralized Power System Figure 16.36: Solutions. During the next few decades, we will probably shift from dependence on a centralized macropower system, based on a few hundred large coal-burning and nuclear power plants to a decentralized micropower system, in which electricity is produced by a large number of dispersed, small-scale, local power generating systems. Some of the smaller systems would produce power on site; others would feed the power they produce into a modern electrical distribution system. Over the next few decades, many energy and financial analysts expect a shift to this type of power system, largely based on locally available renewable energy resources. Question: Can you think of any disadvantages of a decentralized power system? Fig. 16-36, p. 430

Small solar-cell power plants Bioenergy power plants Wind farm Fuel cells Rooftop solar- cell arrays Solar-cell rooftop systems Smart electrical and distribution system Figure 16.36: Solutions. During the next few decades, we will probably shift from dependence on a centralized macropower system, based on a few hundred large coal-burning and nuclear power plants to a decentralized micropower system, in which electricity is produced by a large number of dispersed, small-scale, local power generating systems. Some of the smaller systems would produce power on site; others would feed the power they produce into a modern electrical distribution system. Over the next few decades, many energy and financial analysts expect a shift to this type of power system, largely based on locally available renewable energy resources. Question: Can you think of any disadvantages of a decentralized power system? Commercial Small wind turbine Residential Industrial Microturbines Fig. 16-36, p. 430

Bioenergy power plants Wind farm Small solar-cell power plants Bioenergy power plants Wind farm Solar-cell rooftop systems Commercial Fuel cells Rooftop solar- cell arrays Residential Small wind turbine Smart electrical and distribution system Microturbines Industrial Stepped Art Fig. 16-36, p. 430

Solutions: Making the Transition to a More Sustainable Energy Future Figure 16.37: Energy analysts have made a number of suggestions for helping us make the transition to a more sustainable energy future (Concept 16-9). Questions: Which five of these solutions do you think are the most important? Why? Fig. 16-37, p. 431

Economics, Politics, Education, and Sustainable Energy Resources Government strategies: Keep the prices of selected energy resources artificially low to encourage their use Keep energy prices artificially high for selected resources to discourage their use Consumer education

What Can you Do? Shifting to More Sustainable Energy Use Figure 16.38: Individuals matter. You can reduce your use and waste of energy. Questions: Which three of these items do you think are the most important? Why? Which things in this list do you already do or plan to do? Fig. 16-38, p. 432

Three Big Ideas We should evaluate energy resources on the basis of their potential supplies, how much net useful energy they provide, and the environmental impacts of using them. Using a mix of renewable energy sources—especially solar, wind, flowing water, sustainable biofuels, and geothermal energy—can drastically reduce pollution, greenhouse gas emissions, and biodiversity losses.

Three Big Ideas Making the transition to a more sustainable energy future will require sharply reducing energy waste, using a mix of environmentally friendly renewable energy resources, and including the harmful environmental costs of energy resources in their market prices.